9) Army of Ghosts/Doomsday
Ask any Doctor Who fanboy to tell you the saddest episode (apart from Adric’s demise in the Fifth Doctor story Earthshock) and I can guarantee that The Doctor’s farewell to Rose at the end of Doomsday will be their answer. The mystery that builds in Army of Ghosts is masterfully done, and the battle between the Daleks and the Cybermen is possibly one of the best moments in sci-fi history, especially the epic roasting that goes on between the two. But all of that pales in comparison to the final moments of the episode, in which The Doctor and Rose are forced to say goodbye forever, with Rose being trapped on a parallel Earth. I’ve watched this scene a million times, and each time I always find myself in tears. The emotional impact coupled with fan service is what makes this episode a classic for fans of the show. An absolute heart-breaker.